1. Technical Field
The present invention relates to a driving method for a laser light source device, a laser light source device, an image display device, a monitor device, and an illumination device.
2. Related Art
As a light source used for a projection-type image display device, a discharge lamp (e.g., extra-high-pressure mercury lamp) is generally used.
However, in such a discharge lamp, there is a problem in that the lifetime of the discharge lamp is comparatively short, the scope of color reproducibility is narrow, or the like.
In recent years, a projection-type image display device that includes a laser light source emitting a monochromatic light has been proposed instead of the discharge lamp.
The laser light source is used in combination with a wavelength conversion element (second-harmonic generation element (SHG)) that obtains light having a half-wavelength of the emitted light.
In the above-described wavelength conversion element, there is a problem in that the scope of the temperature acceptability is narrow, furthermore, in that it is impossible to obtain stabilized output when the temperature condition is varied due to the influence of an ambient temperature.
As disclosed in Japanese Unexamined Patent Application, First Publication No. 2000-228552, a laser device that obtains stabilized laser output has been proposed
In the laser device, a mechanism for detecting and controlling the temperature is formed, and the temperature of the resonator including the wavelength conversion element is varied in accordance with an ambient temperature, for example, using a Peltier element.
As described above, since the scope of the temperature acceptability of the wavelength conversion element is narrow, the wavelength conversion element does not operate desirably until the temperature of the wavelength conversion element reaches a predetermined temperature (constant value). Therefore, desired laser light can not be obtained.
Furthermore, in the case of using the laser light as the light source of the projection-type image display device, it is desirable to obtain quick illumination of the laser light.
If the temperature of the wavelength conversion element is controlled to be a predetermined value using the Peltier element, it is possible to obtain a desired laser light.
However, in the Peltier element, there are problems in that it takes time for the temperature of the wavelength conversion element to reach a predetermined temperature, and it is difficult to obtain desired laser light in a short time.
Also, it is possible for the wavelength conversion element to be directly heated by using a heater instead of the above-described Peltier element. However, there are problems in that the overshoot amount of temperature in relative to a predetermined temperature occurs due to an upsurge of the temperature. As a result, it takes time for the temperature of the wavelength conversion element to stabilize at a predetermined temperature.